Freshly packed tomato sauce

ABSTRACT

A process for preparing fresh tomato sauce and the sauce prepared thereby. The sauce has a fresh taste and has good viscosity even though diced tomatoes provided therein are not subjected to an enzyme deactivation heating step. In the process, diced tomatoes and a tomato puree are combined in a kettle including firming salts, water and pectinase.

This is a divisional of Ser. No. 08/905,281 filed Aug. 1, 1997, now U.S.Pat. No. 5,902,616, which is a continuation of Ser. No. 08/511,429 filedAug. 4, 1995, which is now abandoned.

BACKGROUND OF THE INVENTION

Tomatoes have recently received attention as a healthful food,particularly in view of the carotenoids which they contain. Popularsources of tomatoes in the diet are spaghetti and other red pastasauces. Many consumers prefer tomato sauces which are freshly preparedbecause of improved taste. However, a difficulty encountered in thecommercial preparation of fresh sauces is that breaking or cutting oftomatoes, eg, during dicing or crushing, especially breaking or cuttingthe tomato skins, causes the release of enzymes which can result in arapid and usually undesirable decrease in the viscosity of the product.Consequently, heating to elevated temperatures is used to deactivatethese enzymes, with the resulting loss of taste found in processed, asopposed to fesh packed, sauces.

Using fresh tomato products in preparing a tomato sauce (particularlycalcium-treated raw diced tomatoes) can result in the sauce gelling.This is a result of the pectin and pectin-related enzymes not beingdeactivated in the raw tomatoes by heat. Pectin exudes from the rawtomatoes and combines with the available calcium to form a calciumpectate gel. It is usual in the practice of making a spaghetti sauce touse canned or aseptically processed diced tomatoes. The heat processingof the diced tomatoes inactivates the pectin enzymes and sets the pectinin the diced tomatoes. But again, heat processing generally has a impacton taste.

Generally, the best diced tomatoes are made using calcium chloride tofirm the dices prior to processing. The calcium treated diced tomatoescan be a source of calcium for the gelling formation, although mosttomato products contain enough calcium for gel formation to occur evenwithout an additional source of calcium. The source of pectin is theunprocessed diced tomatoes. Pectin can also come from any fresh pureeused in making the sauce although the main source of the excess pectinrelated to the gel has been identified as coming from the raw dicedtomatoes.

Two enzymes which have been implicated in the above are pectin methylesterase, which catalyzes cleavage of methoxy groups from pectin, andpectinase (also known as polygalacturonase or PG) which catalyzesdepolymerization of the cleaved pectin molecules, which causes thereduction in viscosity. It is the demethoxylated pectins which are mostsuseptible to forming gels by combining with calcium ions.

Pectinase is sometimes used to degrade soluble and insoluble pectinswith varying degrees of esterification for viscosity reduction,clarification, and depectinization and maceration of plant tissue in theproduction of fruit and vegetable juices. It is known that pectin willbe deactivated by depolymerization by a small amount of pectinase.

It is documented that raw garlic and onion will under specified processconditions cause a tomato product (i.e., a sauce) to gel. U.S. Pat. No.4,547,375, to Mersfelder et al. addresses how to prevent these gelsand/or use these types of gels to thicken tomato based products.Mersfelder et al. disclose using the gelation mechanism provided byreleasing methyl pectin esterase from onion and garlic to demethoxylatethe pectin available in the tomato based product to generate a supply oflow methoxyl pectin to increase the viscosity of the sauce. They alsodisclose that in sauces wherein the tomatoes were initially heat treatedto inactivate the enzymes, gelling can be prevented by, e.g., a) heatingthe onion or garlic prior to their addition to the sauce or b) theaddition of pectinase.

Crandal et al. U.S. Pat. No. 5,206,047 recognized that high rapid heattreatment of pectin-containing juices will prevent gelling. Crandal etal. were confronted with the fact that the product they wanted to makecould not tolerate a high heat manufacturing process without losing itsproduct benefit. Their solution was to subject their product to highshear to destroy or prevent the gel. Unfortunately, high shear tends todestroy the appearance of distinct diced tomatoes in a sauce. Moreover,to subject a fresh pack tomato based sauce to sufficient heat in a shortenough time to prevent some of the gelation would produce a product thatlacked the flavor and texture benefits derived from making the productat lower temperatures, but results in the product having an undesirabletexture because of the gel.

SUMMARY OF THE INVENTION

The present inventors have found that even when fresh garlic and onionhave been treated to prevent the release of pectin methyl pecterase andthereby prevent them from causing gelling in the tomato products, gelsstill occur in the fresh pack spaghetti sauces containing previouslynon-heat processed raw diced tomatoes. Raw diced tomatoes treated withcalcium chloride to insure their firmness during the sauce processingare particularly susceptible to such gelling. The invention is directedto a process for producing a fresh pack tomato based sauce, preferablywith portions of raw diced tomatoes, fresh garlic and fresh onion, andhaving a fresh taste and a desirable viscosity without the undesirablegelling.

In accordance with the invention, a fresh pack tomato sauce is madeusing cut or broken tomatoes, eg tomato dices, pieces, purees or pastes,by adding the broken tomatoes to a vessel and also, either before orafter the addition of the broken tomatoes, adding pectinase. Preferably,the broken tomatoes are in the form of raw diced tomatoes (with orwithout added calcium for firming). Desirably, fresh onion, and freshgarlic are also added. The broken tomatoes, eg raw diced tomatoes, andpreferably also the fresh onion and garlic, are added without gelling byadding a pectinase enzyme to the vessel prior to adding the dicedtomatoes, fresh garlic, and fresh onion. At least a portion of thebroken tomatoes is not heat treated to deactivate pectin-relatedenzymes. Preferably, substantially none of the diced tomatoes are heattreated to deactivate pectin-related enzymes.

The preferred method of enzyme addition is to add the pectinase to waterand the optional calcium salt such as calcium chloride in the kettle,then to add the raw tomatoes for a short period of time (usually 1 to 5minutes) and then to add a puree of fresh tomatoes and the rest of thesauce ingredients. The sauce can be held for periods of half to onehour, preferably at about 110° F. without causing an undesirable gel toform in the finished sauce or a loss of viscosity. The effective amountof the enzyme ranges from 0.01% to about 1% of the total weight of thesauce.

It is desirable that the addition of pectinase to the sauce be effectedunder controlled conditions. It has unexpectedly been found that the gelwas completely and consistently eliminated in the fresh pack tomatosauce with added raw diced tomatoes, fresh garlic, and fresh onion, yetthe viscosity of the sauce was good. This finding was especiallysurprising in view of the fact that pectinase is used to decreaseviscosity and is implicated in the decrease in viscosity which oftenresults naturally once a tomato has been cut if the product is not soonheated to a high enough temperature to deactivate the enzyme. Thus, useof pectinase according to the invention permits the sauce to have afresh taste by rendering unnecessary the usual enzyme-deactivation (andtaste impairing) heat treatment, while at the same time permitting thesauce to maintain a desirable viscosity and texture. Althoughsterilization prior to packing is usually necessary, heat processing canbe kept to a minimum in making the sauce commercially sterile.

It was surprising that one could add pectinase to a sauce that wasdepending on the properties of pectin for its viscosity since it wasexpected that adding a pectinase to the sauce would adversely affect theviscosity of the sauce. While not wanting to be bound by theory, it isbelieved that the use of pectinase in the present invention limits thepectin/calcium interaction so that the original viscosity of the pureeis maintained, but the pectin being added to the sauce by the rawtomatoes does not gel. The pectinase is not being used to destroy thetomato tissue of the diced tomatoes. Thus, pectinase is being used inconjunction with a low heat process to stabilize tomato sauce viscosityand tomato dice integrity instead of its common use to destroy eitherviscosity and/or plant tissue. The sauce is aseptically processed and ispacked in glass or cans and is shelf stable at room temperature forextended periods of time.

If desired, mixtures of enzymes may be used including, In addition topectinase, enzymes such as cellulase or hemicelllulase.

For purposes of the invention, heat deactivation of pectin enzymes isconsidered to occur at temperatures of 180° F. or more.

In order to preserve the fresh taste of the product, it is especiallypreferred that no tomato ingredients be used which have been previouslyheated, ie, heated outside of the immediate sauce preparation procedure.

For a more complete understanding of the above and other features andadvantages of the invention, reference should be made to the followingdetailed description of preferred embodiments and to the accompanyingdrawings.

DETAILED DESCRIPTION OF THE INVENTION

The tomatoes used in the invention are preferably freshly picked.

Pectinase, also known as PG or polygalacturonase, is available under thebrand name Pectinase AT from Solvay Enzymes of Elkhart, Ind. PectinaseAT has an activity of 150,000 ADJU/gram. ADJU's are apple depectinasejuice units. Another enzyme which may be used is sold as Clarex L, alsoby Solvay, and has an activity of 15,000 ADJU/ml. Clarex ML is apectinase having a pectinase activity of 40,000 ADJU, which alsocontains hemicellulase and cellulase enzymes. The Clarex ML productshould be used in the present invention at approximately four times theamount of the Pectinase AT enzyme. The activities ratio of pectinase tocellulase in the Clarex ML product is 10:1 whereas the activities ratioof pectinase to hemicellulase in the Clarex ML product is 1:4. The ratioof activities for hemicellulase to cellulase in Clarex ML is 40:1. Thepectinase activity in the enzyme preparation may, for example be withinthe range of from 35,000 to 150,000 ADJU/gram. from eg Pectinase may beobtained from Quest, International as Biopectinase. Pectinase may alsobe obtained from Novo Nordisk of New York, N.Y.

The pectinase may be fungal or from plants such as tomatoes and otherfruits or vegetables. Fungal pectinase is preferred. Pectinase is usedat a level of from 0.005 to 0.2 weight percent of the final sauce. Theamount of pectinase used may be adjusted based on the ambienttemperature which the tomatoes experience prior to dicing since highertemperatures can increase pectinase activity.

If it is desired to use a freshly prepared tomato puree in preparing thesauce, in addition to diced or other broken tomatoes, it may bedesirable to heat the puree prior to addition to the vessel. If desired,this may be conducted at temperatures high enough to deactivate enzymes,without departing from the present invention since the diced tomatoeswill still contain active enzymes which induce the problematic gelformation to which the present invention provides a solution.

Preferably at least 10 wt % (based on the weight of the final sauceproduct) and more preferably from 20-45 wt. % of tomatoes in the sauceare subjected to temperatures which do not exceed 180° F., preferably170° F., especially 150° F. prior to sterilization. Commercialsterilization is desirably carried out by heating at between 195 and200° F. for about 10-20 minutes. For instance, the sauce can be heatedat 195° F. for 10 minutes, at 200° F. for 5 minutes or at 185° F. for 15minutes. Desirably, the exposure of the sauce to high temperatures isminimized to preserve the fresh taste.

The amount of diced tomato preferably ranges from 10 to 40 wt % based onthe weight of the final sauce. Tomato puree may be used at from 5 to 45wt % basis final sauce, e.g., 30-45 wt. %. Water will typically be addedat from 10-45 wt %.

Spaghetti sauces often include one or more vegetable oils. Typicalexamples of appropriate vegetable oils include corn oil, olive oil,canola oil and soybean oil, although almost any vegetable oil can beused. The oil may be used at from 0 to 15 wt. %, especially from 0.5 to12 wt. %. and more narrowly from 2 to 9 wt. %. However, the sauce mayalso be free of added triglyceride oil or fat. If trigylcerides arepresent it is preferred that they be in the form of vegetable oil ratherthan animal fat.

Sauces prepared in accordance with the invention will desirably have aBostwick viscosity of from 5 to 7 cm, especially from 5.5 to 6.5 cm,most preferably 6 cm.

The Bostwick viscosity may be determined as follows. The sauce is placedin a viscometer instrument called a Bostwick Consistometer. The BostwickConsistometer must be at room temperature (25 C) and be clean and dry.It must be leveled. A small carpenter's level works well. The puree orpaste is diluted to 12 brix and mixed until there are no visible lumpsof tomato puree and/or paste. The chamber is filled full. The excessmaterial is scraped off of the top of the chamber with a straight edge.Release the gate and time for 30 seconds. Record the distance the tomatopuree/paste has traveled in cm. The sauce will move to a distancecorresponding to its viscosity; the higher the viscosity, the lessdistance the paste will move. The Bostwick number is obtained bymeasuring the distance as callibrated on the instrument. The solublesolids of the sauce will typically range from 10 to 16, preferably from12 to 15 brix.

The pH of the sauce may be adjusted as desired using edible acidsincluding citric, malic, lactic, acetic or gluconic acids. If necessary,the pH may be buffered using a buffer system such as citric acid/sodiumcitrate, gluconic acid/sodium gluconate, acetic acid/sodium acetate, ormalic acid/sodium malate systems. The pH of the sauce of the inventionmay range from about 4 to about 6, especially from 4 to 5.

In addition to Allium vegetables such as onion and garlic, otheringredients which may be used in the sauce include table salt,sweeteners such as sucrose, pepper and garlic and onion powders. Ifdesired, the Allium ingredients may be blanched, eg heated at atemperature of above 160° F. prior to addition to the tomato ingredientsof the product.

Seasonings and spices may include pepper, such as black pepper and redpepper, basil, dry basil, oregano, thyme, bell pepper, celery, bay leaf,fennel and parsley. Chopped vegetables, such as green and red peppersand carrots, and meats, such as ground beef, may be included, ifdesired.

The sauce of the invention is typically prepared by adding freshly dicedtomatoes to a kettle to which has already been added water, firmingsalts and pectinase. Desirably, the diced tomatoes are treated as earlyas possible in the process with the firming salts. A fresh puree whichhas a soluble solids content of about 20 brix is then added. The pureeis preferably at 20 brix, eg from 15 to 25 brix rather than the moretypical 32 brix, so as to be subjected to less heat during theevaporation process. However, 31 or 32 brix paste could also be used.The puree will preferably have been subjected to a break temperature ofapproximately 200° F. for 5 to 10 minutes. The sauce is held for an hourat from room temperature up to 110° F. or another appropriatetemperature after which the sauce is sterilized and packed. Preferably,the sauce is subjected to commercial sterilization conditions which areless severe, to enhance fresh taste.

The order of addition of ingredients may be varied, so long as theviscosity is not undesirably diminished. For instance, the dicedtomatoes can be added to the firming salt and water and mixed, afterwhich pectinase can be added and mixed, after which the puree, spicesand remainder of ingredients can be added. Alternatively, the pectinasecan be added immediately after the puree.

The diced tomatoes are exposed to firming salts to preserve theirviscosity. Calcium chloride is a preferred firming salt. Anotherpreferred firming salt is calcium citrate. Others include mono calciumphosphate and calcium lactate. Calcium chloride is used in an amount notto exceed 0.222 wt % of the sauce , preferably from 0.095 wt % to 0.222wt %.

To ascertain whether a sauce is to be considered gelled, i.e., to possesan undesirable gel, gel strength assessment is determined by a visualanalysis of the cooled product in a jar. A gelled product retains theshape of the jar and pulls away cleanly from the side of the jar whentipped or rotated. The product surfaces appear shiny on gelled products.A non-gelled product appears uniformly pulpy and not shiny.

A visual assessment of the jarred product is made individually by one ormore, preferably more than one, especially four, people familiar withidentifying gelling in tomato based products. The scale used is a sixpoint scale adopted from gel assessments made by Crandal et al. in U.S.Pat. No. 5,206,047. They refer to a Gel Evaluation test by Redd et. al."Quality Control Manual for Citrus Processing Plants." (1986 Intercit,Inc.). The Crandal et al. and Redd et al. references are incorporatedherein by reference.

The scale is as follows:

0=Product of uniform appearance, contains no gel lumps.

1=Product with a few small gel lumps but no tendency to mound.

2=Product contains some gelled lumps with a slight tendency to mound.

3=Product has a definite degree of gelation with a slight tendency tomound but does not retain the shape of the container.

4=Product is over 75% gelled with a definite retention of the shape ofthe container.

5=Product is 100% gelled with the product retaining the fine detailedshape of the container.

Products with a gel score above 3 are not considered gelled. Productswith a score of 3 are considered borderline and could be rejected from aquality point of view as having an objectionable amount of gel. Theamount of gel expected ranges in the 2 or below category. While scoresof 3 might be accepted, adjustments in the amount of enzyme would beconsidered.

EXAMPLE 1

Example 1 illustrates the preferred method of gel prevention in theproduction of fresh pack tomato sauces processed at optimum temperaturesto retain the sauce freshness without compromising the product stabilityor safety.

A tomato sauce product is prepared according to the following formula:

    ______________________________________                                        Ingredient            Wt. by %                                                ______________________________________                                        Water                 29.05                                                   Fresh Tomato Puree    30.00                                                   Raw Diced Tomatoes    30.00                                                   Sweetener             6.00                                                    Fresh Onions          1.00                                                    Fresh Garlic          .50                                                     Pectinase*            .05                                                     Other Seasonings and Minor Ingredients                                                              3.40                                                    Total                 100.0                                                   ______________________________________                                         *Varies from .005 to .20 depending on the raw tomatoes.                       *The actual amount of the pectinase is also dependent on the activity of      the enzyme.                                                              

The fresh raw tomatoes are diced and conveyed immediately to a kettlewaiting with the pectinase, firming salts, and water. The mixture isallowed to mix at ambient temperature for a minimum of 5 to 10 minutes.Fresh onions and garlic are optionally sauteed (i.e. blanched) and addedto the mixture. The fresh tomato puree is pumped from the concentratorto the kettle and the remaining fresh ingredients (basil), seasoningsand other minor ingredients are added. To preserve freshness the sauceis held at 110° F. for up to an hour. The batch is immediately heatedvia a heat exchanger to 195° F., filled into the jars and held for theminimum time (about ten minutes). Once the product has been exposed toat least minimum commercial sterilization conditions, it is immediatelycooled to ambient temperature.

When this process is followed without the use of the pectinase or apectinase-containing enzyme mix, the sauce gells on cooling. The saucesmade with from 10 to 40 percent raw tomatoes do not gel when thepectinase or pectinase containing enzyme is used in this process.

Instead of holding the batch at 110° F., it may be held at roomtemperature or up to 110° F. or from 150 to 175° F. for up to an hour.The lower temperatures are preferred.

EXAMPLE 2

Example 1 illustrates the preferred method of gel prevention in theproduction of fresh pack tomato sauces processed at optimum temperaturesto retain the sauce freshness without compromising the product stabilityor safety. However, a part of the discovery of the invention is that anenzyme mixture containing a combination of pectinase, cellulase andhemicellulase is effective in preventing the gelation of fresh packtomato sauces.

A tomato sauce product is prepared according to the following formula:

    ______________________________________                                        Ingredient            Wt. by %                                                ______________________________________                                        Water                 29.05                                                   Fresh Tomato Puree    30.00                                                   Raw Diced Tomatoes    30.00                                                   Sweetener             6.00                                                    Fresh Onions          1.00                                                    Fresh Garlic          .50                                                     Enzyme Mix* (Pectinase, Cellulase and                                                               .20                                                     Hemicellulase)                                                                Other Seasonings and Minor Ingredients                                                              3.40                                                    Total                 100.00                                                  ______________________________________                                         *Varies from .005 to .20 depending on the raw tomatoes.                       *The actual amount of the pectinase blend is also dependent on the            activity of the enzyme.                                                  

The fresh raw tomatoes are diced and conveyed immediately to a kettlewaiting with the enzyme mix (pectinase, cellulase and hemicellulase),calcium chloride and water. The, mixture is allowed to mix at ambienttemperature for a minimum of 5 to 10 minutes. Fresh onions and garlicwhich are optionally sauteed (i.e. blanched) are added to the mixture.The fresh tomato puree is pumped from the concentrator to the kettle andthe remaining fresh ingredients (basil), seasonings, and other minoringredients are added, To preserve freshness the sauce is held at roomtemperature for up to an hour. The batch is immediately heated via aheat exchanger to 195° F., filled into 24 oz. jars and held for theminimum time (about ten minutes). Once the product has been exposed tothe commercial sterilization conditions, it is immediately cooled toambient temperature.

When this fresh pack process is followed without the use of thepectinase or a pectinase containing enzyme, the sauce gels on cooling.Sauces made with from 10 to 40 percent raw tomatoes do not gel when thepectinase or pectinase-containing enzyme mix are used in this process.

The inventors have found that not all gels of tomato sauces are pectingels. Particularly when processed tomatoes are used in making the tomatosauce, cellulose gels were found. These were confirmed by dissolving thegels with cellulose. Therefore it was felt that some cellulase would beuseful in controlling the tomato sauce gel. However, we have found thatthe gel from pectin was on such a larger scale than gels from cellulosethat the pectinase become the preferred enzyme of choice.

EXAMPLE 3

The procedure of Example 1 is followed, except that the dice amounts andenzyme amounts are varied as set forth below. Bostwick viscosity valuesare measured for the various sauces, as set forth below.

    ______________________________________                                        Example Dice Amount Enzyme wt. %                                                                              Sauce Bostwick                                ______________________________________                                        A       11.4        0.005-0.10  6.1                                           B       13.2        0.010-0.030 5.5                                           C       16.0        0.010-0.030 5.5                                           D       32.7        0.011-0.100 5.6                                           E       12          0.000       GEL                                           ______________________________________                                    

The presence of a gel is determined by four people familiar with thedetection of gels in tomato products using the procedure set forthabove.

EXAMPLE 4

Sensory data for a fresh pack sauce prepared according to Example 1 iscompared with that for commercially available, remanufactured,tomato-based sauce made by heating substantially all of the cut tomatoesshortly after they have been picked and without addition of pectinase.The remanufactured product is a fresh pack formula made with heattreated tomato dices and 31 brix paste. The results are as follows:

    ______________________________________                                                      Con-    Chunky  No. of To-                                                                            Processed                               Product                                                                              Color  sistency                                                                              Appearance                                                                            mato Pieces                                                                           Tomato Flavor                           ______________________________________                                        Fresh  4      4       6       5       3.3                                     Remanfctd                                                                            4      4.5     4       3.5     4.5                                     ______________________________________                                         Key:                                                                          Color: 1 = orange 5 = red 9 = brown                                           Consistency: 1 = very thin 9 = very thick                                     Chunky: 1 = smooth looking 9 = chunky looking                                 Amount of Tomato Pieces: 1 = very few 9 = very chunky                         Both formulas started with the same amount of tomatoes                        Processed Flavor: 1 = Fresh 5 = Processed 9 = Overcooked                 

The fresh pack sauce is fresher than the remanufactured product. Thefresh pack sauce retains more tomato piece integrity. The remanufacturessauce has an insignificant amount of higher consistency.

It will be noted that the enzyme mixture requires about 4 times moreenzyme than the straight pectinase. The reason for this is that thesource of the pectinase enzyme may have a much higher activity levelthan the mixed enzyme.

The firming agent mentioned relies on the calcium in it to interact withthe raw diced tomatoes to give them firmness. This same calcium willcombine with the low methoxy pectin in the tomato sauce to form verytight gels. The pectinase then becomes key to having firm tomatoes witha non gelled viscous sauce.

It should be understood, of course, that the specific forms of theinvention herein illustrated and described are intended to berepresentative only, as certain changes may be made therein withoutdeparting from the clear teaching of the disclosure. Accordingly,reference should be made to the following appended claims in determiningthe full scope of the invention.

What is claimed is:
 1. A freshly packed, sterilized tomato saucecomprising diced tomatoes and pectinase, said tomatoes not having beenpectin enzyme heat deactivated prior to sterilization, said fresh packedtomato sauce having Bostwick viscosity of from 5 to
 7. 2. The tomatosauce according to claim 1 wherein the fresh packed tomato sauce is nota gel and has a Bostwick viscosity of from 5.5 to 6.5.
 3. The sauceaccording to claim 1 comprising from 10 and higher wt. % non heattreated diced tomatoes.